Complex oxides exhibit a variety of unusual physical properties, which can be used for designing novel electronic devices. Here we fabricate and study experimentally nanoscale superconductor/ferromagnet/ superconductor junctions with the high-$T_c$ cuprate superconductors ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ and the colossal magnetoresistive (CMR) manganite ferromagnets ${\mathrm{La}}_{2/3}{X}_{1/3}{\mathrm{MnO}}_{3+\delta }(X=\mathrm{Ca}\text{or}\mathrm{Sr})$. We demonstrate that in a broad temperature range the magnetization of a manganite nanoparticle, forming the junction interface, switches abruptly in a monodomain manner. The CMR phenomenon translates the magnetization loop into a hysteretic magnetoresistance loop. The latter facilitates a memory functionality of such a junction with just a single CMR ferromagnetic layer. The orientation of the magnetization (stored information) can be read out by simply measuring the junction resistance in a finite magnetic field. The CMR facilitates a large readout signal in a small applied field. We argue that such a simple single-layer CMR junction can operate as a memory cell both in the superconducting state at cryogenic temperatures and in the normal state up to room temperature.

• Received 8 April 2019
• Revised 28 May 2019

DOI:https://doi.org/10.1103/PhysRevB.99.214510